Piston expander



April 26, 1938. J. B. EVANS PISTON EXPANDER Filed March 27, 1957 11arty/M 4.

Patented Apr. 26, 1938 uNiTEo [STATES h rrs'ron ExPAnDEn 7 James B.Evans; South Williamsport, Pa. Application March 27, 1937', Seriai No.133,431

7 Claims. (01.. 309-12) My invention relates to animprovement in pistonexpanders.

After an automobile engine has been used for a period of time, thecylinder walls wear somewhat and also the wrist-pins of the pistonsWear, and as a result a knock which is generally known as a piston slapdevelops. In order to correct this piston slap, it is necessary eitherto replace the pistons with new pistons or to expand the skirt of theold piston so that it will follow the cylinder wall more closely. It hasbeen found that by expanding the piston skirt, very satisfactory resultsmay be obtained incorrecting piston slaps by again making the skirtproperly fit within the cylinder, so that it may reciprocate thereinwithout knockingv on the side walls at the top of the piston stroke.

An object of my invention is to provide a'piston expander which may bereadily adjusted to expand the piston skirt within one-thousandth ofaninch or less.

A further object is to provide a piston expander which may be placedwithin the skirt of a conventional aluminum-alloy or steel-alloy pistonor any other piston in position so that after the expander has beenadjusted, it may not be shaken loose and drop from the piston.

A further object is to provide a piston expander which will expand apiston skirt equally on both sides of the customary slot through theskirt.

In the accompanying drawing:

Fig. 1 is a front elevation, partly in section showing my pistonexpander in place within the piston skirt;

Fig. 2 is a side elevation partly in section showing the pistonexpander;

Fig. 3 is a bottom plan view; and

Fig. 4 is a disassembled view showing the several parts of the pistonexpander, one part being broken away.

A conventional piston 2 is provided with a slot 4 in the skirt thereof,or which may be cut in the skirt if it is not provided in the piston asa part of the regular equipment. The piston is also provided withcustomary bearing 6 to hold a wrist-pin passing therethrough and throughthe upper end of a connecting-rod (not shown).

The bearing 6 is provided with conventional shoulders 8 and H] on theinside of the piston, which shoulders are primarily a part of thecasting from which the piston is made, and to provide a suitable basefor the bearing 6.

In preparing a piston for the use of my piston expander, I drill twosubstantially small holes through the piston skirt near the lower endthereof approximately beneath the bearing 6 and diametrically oppositeone another. These holes. maybe of any suitable size, but must beapproximately of the "-"same -diameter' as the diameter of the 'steel'wire which I bend and utilize to make my piston expander. The steel wirepart oi the piston expander is provided with an end II which is sharplybent and is adapted to fit within the holes which have previously beenbored in'the lower portion of the piston'skirt. The steel wire fromthis'point extends approximately straight, and this straight portionH-covers approximately the distanceof an arc of thirty degrees (30) atwhich point IS the steel wire is bent atan angle from the straightportion 14 and extends approximately straight from the angle [6 toanotherangle l8 of approxi mately the-same'degree as the angle 16, fromwhich angle the wire extends straight for a short distance, and is.provided with suitable screwthreads 20.

Another wire, which is identical in itsv configuration is'utllized toextendfrom the other hole which has been bored in the piston skirt 3.After these two portions of the expander have been placed in thediametrically opposite holes, and

suitable nuts 22 have been threaded on to the screw-threaded ends 20, acollar 24 is placed over the screw-threaded ends 20 in position to beengaged by the nuts 22 when they are turned.

These two steel wires or bent pieces as described above, and as clearlydisclosed in Fig. 3; are placed within the piston skirt and forcedinwardly toward the head of the piston until the straight portion l4abuts against the shoulder 8 and the straight portion I'I between thebends l6 and I8 abuts against the shoulder l0 within the piston skirt.This abutting relation between the shoulders 8 and I0 and the straightportions I4 and [l prohibits the. piston expander from being moved to apoint further within the piston.

By turning the nuts 22 to bear against the collar 24, the screw-threadedends 20 and consequently the steel wire portions of the expander areforced outwardly and push against the piston skirt 3 at the points wherethe bent portions 16 and I8 bear against the skirt 3. In this way, thepiston skirt 3 may be forced outwardly, the slot 4 consequently beingwidened as the other portion of the skirt is expanded to a predeterminedamount.

By the position which they assume within the piston skirt, the nuts 22bear against the inside of the piston skirt so that they will remainlocked number of thousandths of an inch, so that it will again fitproperly within the cylinders. I

utilizing hexagonal nuts 22, I have found that a' one-sixth turn ofeither or both of these nuts is satisfactory in expanding a piston thedesired amount. Obviously, if a finer adjustment should be desired,octagonal nuts or nuts having even;

more fiat surfaces could be utilized and yet could be properly locked byabutting against the skirt of the piston. r V

, -I claim:"

LA piston expander including two legs connected to apiston skirt atdiametrically opposed points, a c'ollar enclosing the ends of said legsremote from their points of connection with the piston skirt and formingtherewith an approximate semi-circle, and means tending to'separate theends of the legs and to push them away from said collar. r Y

2. The combination of a piston having an.ex pansible skirt and anexpander including two legs,

one end of each leg being pivotally' secured to the piston skirt atapproximately diametrically opposed points, the otherfends of said legsbeing screw-threaded and adapted to be positioned within a collar,.and'nuts threadedbn said legs and adapted toforce the said legsoutwardly against theinside of the piston skirt.-

'3'. Thecombina-tion of a piston having an expansible skirt andapiston-expander, said-ex,- pander including two spring legs, each ofwhich is pivotally attached to said piston at diametrically opposedpoints, each of'which is screw- Also by.

threaded at the ends thereof remote from said pivotal connections, andeach of which is forced apart at the screw-threaded ends thereof by nutsbearing against a collar.

4. The combination o1 a piston having an expansible skirt and a pistonexpander, said expander including two clips pivotally affixed to thepiston skirt at diametrically opposed points and extendingvin asubstantially semi-circular position and bearing against the insideofsaid piston skirt, said clips being forced apart at their free ends bynuts bearing ag'ainst'a collar surrounding said free ends, andscrew-threaded to the said clips, said nuts bearing against the innerwall of said piston skirt. 7

5. The combination of a 'pistonhaving an expansibleskirt and a pistonskirt expander, said expander including two clips pivoted to the insideof said piston and approximately fitting the internal periphery ofsaidpiston skirt, means for forcing thefree ends of said clipsapart, thesaid clips being of such length that they, may not'be.

pivotally swungout of the; piston skirt. p

6. The'combination of a piston havingan expansible skirt and apistonskirt expander, said expander including spring clips, the combinedlength of which is greater than the length of onehalf of the innerperiphery of the said skirt, said clipsbeing pivoted to the said skirtat diametricall -opposed points and secured together at their free endsby a collar and 'nuts screw-threaded to said clips, said nuts bearingagainst the inner side of said skirt. I

7; A piston skirt expander including two curved legs, oneend of. each ofsaid legs pivoted to a piston skirt at approximately diametrically opposed points, the other ends of said legs extending Within a collar, anda nut'mounted on each of the second-mentioned leg ends and bearingagainst the said collar, the said legs and collar when in adjustedposition being slightly greater than one-halfof the internal peripheryof said piston skirt. 7 p

. JAMES B. EVANS

